There is a technology in which an object is recognized from an image of the object captured by an image capturing section. In such a technology, an appearance feature amount of the object is extracted from the image and then compared with feature amount data of each reference image registered in the recognition dictionary to calculate a similarity degree of the feature amounts. Then, an object equivalent to the reference image having the highest similarity degree is recognized as the object photographed by the image capturing section. In recent years, it has been proposed to apply such an object recognition technology to a checkout system (POS system) of a retail store to recognize commodities purchased by a customer.